/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.config.annotation;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.springframework.lang.Nullable;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.util.Assert;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.HandshakeHandler;
import org.springframework.web.socket.server.HandshakeInterceptor;
import org.springframework.web.socket.server.support.OriginHandshakeInterceptor;
import org.springframework.web.socket.server.support.WebSocketHttpRequestHandler;
import org.springframework.web.socket.sockjs.SockJsService;
import org.springframework.web.socket.sockjs.support.SockJsHttpRequestHandler;
import org.springframework.web.socket.sockjs.transport.handler.WebSocketTransportHandler;

/**
 * An abstract base class for configuring STOMP over WebSocket/SockJS endpoints.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class WebMvcStompWebSocketEndpointRegistration implements StompWebSocketEndpointRegistration {

    private final String[] paths;

    private final WebSocketHandler webSocketHandler;

    private final TaskScheduler sockJsTaskScheduler;
    private final List<HandshakeInterceptor> interceptors = new ArrayList<>();
    private final List<String> allowedOrigins = new ArrayList<>();
    @Nullable
    private HandshakeHandler handshakeHandler;
    @Nullable
    private SockJsServiceRegistration registration;


    public WebMvcStompWebSocketEndpointRegistration(String[] paths, WebSocketHandler webSocketHandler,
            TaskScheduler sockJsTaskScheduler) {

        Assert.notEmpty(paths, "No paths specified");
        Assert.notNull(webSocketHandler, "WebSocketHandler must not be null");

        this.paths = paths;
        this.webSocketHandler = webSocketHandler;
        this.sockJsTaskScheduler = sockJsTaskScheduler;
    }


    @Override
    public StompWebSocketEndpointRegistration setHandshakeHandler(HandshakeHandler handshakeHandler) {
        Assert.notNull(handshakeHandler, "'handshakeHandler' must not be null");
        this.handshakeHandler = handshakeHandler;
        return this;
    }

    @Override
    public StompWebSocketEndpointRegistration addInterceptors(HandshakeInterceptor... interceptors) {
        if (!ObjectUtils.isEmpty(interceptors)) {
            this.interceptors.addAll(Arrays.asList(interceptors));
        }
        return this;
    }

    @Override
    public StompWebSocketEndpointRegistration setAllowedOrigins(String... allowedOrigins) {
        this.allowedOrigins.clear();
        if (!ObjectUtils.isEmpty(allowedOrigins)) {
            this.allowedOrigins.addAll(Arrays.asList(allowedOrigins));
        }
        return this;
    }

    @Override
    public SockJsServiceRegistration withSockJS() {
        this.registration = new SockJsServiceRegistration();
        this.registration.setTaskScheduler(this.sockJsTaskScheduler);
        HandshakeInterceptor[] interceptors = getInterceptors();
        if (interceptors.length > 0) {
            this.registration.setInterceptors(interceptors);
        }
        if (this.handshakeHandler != null) {
            WebSocketTransportHandler handler = new WebSocketTransportHandler(this.handshakeHandler);
            this.registration.setTransportHandlerOverrides(handler);
        }
        if (!this.allowedOrigins.isEmpty()) {
            this.registration.setAllowedOrigins(StringUtils.toStringArray(this.allowedOrigins));
        }
        return this.registration;
    }

    protected HandshakeInterceptor[] getInterceptors() {
        List<HandshakeInterceptor> interceptors = new ArrayList<>();
        interceptors.addAll(this.interceptors);
        interceptors.add(new OriginHandshakeInterceptor(this.allowedOrigins));
        return interceptors.toArray(new HandshakeInterceptor[interceptors.size()]);
    }

    public final MultiValueMap<HttpRequestHandler, String> getMappings() {
        MultiValueMap<HttpRequestHandler, String> mappings = new LinkedMultiValueMap<>();
        if (this.registration != null) {
            SockJsService sockJsService = this.registration.getSockJsService();
            for (String path : this.paths) {
                String pattern = path.endsWith("/") ? path + "**" : path + "/**";
                SockJsHttpRequestHandler handler = new SockJsHttpRequestHandler(sockJsService, this.webSocketHandler);
                mappings.add(handler, pattern);
            }
        } else {
            for (String path : this.paths) {
                WebSocketHttpRequestHandler handler;
                if (this.handshakeHandler != null) {
                    handler = new WebSocketHttpRequestHandler(this.webSocketHandler, this.handshakeHandler);
                } else {
                    handler = new WebSocketHttpRequestHandler(this.webSocketHandler);
                }
                HandshakeInterceptor[] interceptors = getInterceptors();
                if (interceptors.length > 0) {
                    handler.setHandshakeInterceptors(Arrays.asList(interceptors));
                }
                mappings.add(handler, path);
            }
        }
        return mappings;
    }

}
